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United States Patent |
5,687,645
|
Kato
|
November 18, 1997
|
Mechanical pressing machine
Abstract
There is disclosed a mechanical pressing machine in which an unbalanced
inertia force, produced during reciprocal movement of a slider, is
canceled without producing deflection in the whole of the pressing
machine, thereby enhancing dynamic precision. The slider, slidably mounted
at a lower portion of a frame, is connected to a dynamic balancer,
slidably mounted at an upper portion of the frame, by link mechanisms. A
press cam, having a cam surface in contact with cam followers mounted
respectively on the slider and the dynamic balancer, is fixedly mounted on
a cam shaft. Dynamic balancer cams, each having a cam surface in contact
with cam followers mounted respectively on interconnecting points of the
link mechanisms, is fixedly mounted on the cam shaft. The dynamic balancer
is driven to move in a direction opposite to a direction of movement of
the slider, so that an unbalanced inertia force, produced in the moving
slider, is canceled by an oppositely-directed inertia force produced in
the dynamic balancer.
Inventors:
|
Kato; Heizaburo (Shizuoka-ken, JP)
|
Assignee:
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Sankyo Seisakusho Co. (Tokyo, JP)
|
Appl. No.:
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660791 |
Filed:
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June 6, 1996 |
Foreign Application Priority Data
| Jun 19, 1995[JP] | 7-151342 |
| Oct 30, 1995[JP] | 7-281910 |
Current U.S. Class: |
100/282; 72/452.6; 83/615; 83/628; 100/286; 100/292 |
Intern'l Class: |
B30B 001/26 |
Field of Search: |
100/257,282,285,286,292
83/615,628
72/451,452.6
|
References Cited
U.S. Patent Documents
2532320 | Dec., 1950 | Maussnest | 100/282.
|
2857157 | Oct., 1958 | Bonquet | 83/615.
|
3859838 | Jan., 1975 | Karsnak | 100/292.
|
4638731 | Jan., 1987 | Kato | 100/292.
|
4699036 | Oct., 1987 | Henne | 83/615.
|
4852382 | Aug., 1989 | Gietz et al. | 100/286.
|
4967586 | Nov., 1990 | Hecht | 100/292.
|
5467706 | Nov., 1995 | Kato.
| |
5605096 | Feb., 1997 | Kato | 100/292.
|
Foreign Patent Documents |
K16179 | Nov., 1955 | DE | 100/286.
|
Other References
U.S. application No. 08/610,452, Kato, filed Mar. 4, 1996.
|
Primary Examiner: Gerrity; Stephen F.
Attorney, Agent or Firm: Harness, Dickey & Pierce, P.L.C.
Claims
What is claimed is:
1. A mechanical pressing machine comprising:
a slider supported on a lower portion of a frame for sliding movement in a
vertical direction, said slider carrying an upper press die at its lower
surface;
a dynamic balancer supported on an upper portion of said frame for sliding
movement in the vertical direction, said dynamic balancer being equal in
weight to said slider;
a cam shaft rotatably supported on said frame, and extending in a
horizontal direction, said cam shaft being connected at one end thereof to
rotation transmission means;
at least one press cam fixedly mounted on said cam shaft for rotation
therewith, said press cam having a cam surface in contact with cam
followers mounted respectively on an upper surface of said slider and a
lower surface of said dynamic balancer;
at least one pair of link mechanisms provided on opposite sides of said
press cam, respectively, each of said link mechanisms comprising a pair of
first and second links of the same length which are pivotally connected at
one ends thereof to the upper surface of said slider and the lower surface
of said dynamic balancer, respectively, and are pivotally connected
together at the other ends thereof; and
at least one dynamic balancer cam fixedly mounted on said cam shaft for
rotation therewith, said dynamic balancer cam having a cam surface in
contact with cam followers each of which is mounted on the interconnected
other ends of said first and second links of a respective one of said link
mechanisms.
2. A pressing machine according to claim 1, in which said press cam and
said dynamic balancer cam have different shapes from each other, and the
shape of each of said two cams is 180.degree. symmetrical.
3. A pressing machine according to claim 2, in which there are provided one
said press cam and two said dynamic balancer cams.
4. A pressing machine according to claim 2, in which there are provided two
said press cams and one said dynamic balancer cam.
5. A mechanical pressing machine comprising:
a slider supported on a lower portion of a frame for sliding movement in a
vertical direction, said slider carrying an upper press die at its lower
surface;
a dynamic balancer supported on an upper portion of said frame for sliding
movement in the vertical direction, said dynamic balancer being equal in
weight to said slider;
a cam shaft rotatably supported on said frame, and extending in a
horizontal direction, said cam shaft being connected at one end thereof to
rotation transmission means;
at least one press cam fixedly mounted on said cam shaft for rotation
therewith, said press cam having a cam surface in contact with cam
followers mounted respectively on an upper surface of said slider and a
lower surface of said dynamic balancer;
at least one pair of link mechanisms provided on opposite sides of said
press cam, respectively, each of said link mechanisms comprising a pair of
first and second links of the same length one ends of which are pivotally
connected respectively in coaxial relation to said cam followers mounted
respectively on the upper surface of said slider and the lower surface of
said dynamic balancer, and the other ends of said pair of first and second
links being pivotally connected together; and
at least one dynamic balancer cam fixedly mounted on said cam shaft for
rotation therewith, said dynamic balancer cam having a cam surface in
contact with cam followers each of which is mounted on the interconnected
other ends of said first and second links of a respective one of said link
mechanisms.
6. A pressing machine according to claim 5, in which said press cam and
said dynamic balancer cam have different shapes from each other, and the
shape of each of said two cams is 180.degree. symmetrical.
7. A pressing machine according to claim 6, in which there are provided one
said press cam and two said dynamic balancer cams.
8. A pressing machine according to claim 6, in which there are provided two
said press cams and one said dynamic balancer cam.
Description
BACKGROUND OF THE INVENTION
This invention relates generally to a mechanical pressing machine, and more
particularly to a mechanical pressing machine provided with a dynamic
balancing device for balancing an unbalanced inertia force in a
reciprocating mechanism employing a plate cam.
One example of known mechanical presses employing a plate cam is of the
constrained cam type using a yoke mechanism or the like. In such a
mechanical press, a reciprocating member is connected to a follower
portion through a connecting rod, and rotational movement of the plate cam
is converted into reciprocal movement. When the press, employing such a
plate cam, is operated, there develop vibrations due to an unbalanced
inertia force produced by the reciprocal movement of a slider as in a
conventional crank press, so that noises and a positional error are
produced. To avoid these, a dynamic balancing device has usually been used
in the press.
In the conventional dynamic balancing device, an unbalanced inertia force
of the reciprocating slider is canceled by a balance weight (which is
equivalent in weight to the slider) supported through a cam or a link at a
position in opposite phase with a convex portion of the plate cam. With
this construction, the unbalanced inertia force for the whole of the press
is canceled by the balance weight, and vibrations of the press itself
(except the slider and other moving parts) are reduced, so that the press
can be operated at high speed.
In the above conventional pressing machine, however, when attention is
directed to the slider on which an upper die is mounted, the inertia force
F, generated during the reciprocal movement, produces deflection S
(S=F.times.K) in accordance with rigidity (spring constant) K of a load
propagation path (usually from the follower to a press frame through the
driver). Generally, this deflection S becomes the largest near to a lower
dead center, so that the dimension of the slider is elongated downwardly,
thereby adversely affecting the precision at the lower dead center. This
deflection S is proportional to the inertia force, and therefore increases
with the increase of the speed. Thus, although the pressing machine is
made apparently quiet by the provision of the dynamic balancing device,
the evaluation of the dynamic precision (for example, from the viewpoints
of the lower dead center precision, a coining precision and so on) has not
been satisfactory.
To overcome these problems, Applicant of the present application has
earlier proposed mechanical pressing machines provided with a dynamic
balancing device of high dynamic precision in Co-pending U.S. patent
application Ser. Nos. 08/293,752 and 08/293,815.
SUMMARY OF THE INVENTION
It is an object of this invention to provide a mechanical pressing machine
which is simpler in construction, and can achieve higher precision than
the above earlier-proposed mechanical pressing machines.
According to the present invention, there is provided a mechanical pressing
machine comprising:
a slider supported on a lower portion of a frame for sliding movement in a
vertical direction, the slider carrying an upper press die at its lower
surface;
a dynamic balancer supported on an upper portion of the frame for sliding
movement in the vertical direction, the dynamic balancer being equal in
weight to the slider;
a cam shaft rotatably supported on the frame, and extending in a horizontal
direction, the cam shaft being connected at one end thereof to rotation
transmission means;
at least one press cam fixedly mounted on the cam shaft for rotation
therewith, the press cam having a cam surface in contact with cam
followers mounted respectively on an upper surface of the slider and a
lower surface of the dynamic balancer;
at least one pair of link mechanisms provided on opposite sides of the
press cam, respectively, each of the link mechanisms comprising a pair of
first and second links of the same length which are pivotally connected at
one ends thereof to the upper surface of the slider and the lower surface
of the dynamic balancer, respectively, and are pivotally connected
together at the other ends thereof; and
at least one dynamic balancer cam fixedly mounted on the cam shaft for
rotation therewith, the dynamic balancer cam having a cam surface in
contact with cam followers each of which is mounted on the interconnected
other ends of the first and second links of a respective one of the link
mechanisms.
The one ends of the first and second links of the link mechanism can be
pivotally connected respectively in coaxial relation to the cam followers
mounted respectively on the upper surface of the slider and the lower
surface of the dynamic balancer.
Therefore, in the present invention, by providing the dynamic balancer
which moves in a direction opposite to the direction of movement of the
slider when the slider moves, an unbalanced inertia force, produced during
the reciprocal movement of the slider, is canceled, and deflection of the
whole of the pressing machine is reduced, thereby enhancing the dynamic
precision, and vibrations and noises are reduced. And besides, the
pressing machines of the invention are simpler in construction, and
achieve higher precision as compared with the above earlier-proposed
pressing machines, and the slider and the dynamic balancer are moved
simultaneously not by sliding contact but by rolling contact between the
cams and the cam followers, and therefore the transmission efficiency is
enhanced, and the high-speed operation can be suitably carried out.
BRIEF DESCRIPTION OF THE DRAWINGS
FIG. 1 is a schematic, cross-sectional view of one preferred embodiment of
a mechanical pressing machine of the present invention as viewed from a
front side thereof;
FIG. 2 is a schematic, cross-sectional view of the mechanical pressing
machine as viewed from a side thereof;
FIGS. 3 and 4 are views similar to FIG. 1, explanatory of the operation of
the pressing machine;
FIG. 5A is a schematic, cross-sectional view of another embodiment of a
mechanical pressing machine of the invention as viewed from a side
thereof;
FIG. 5B is a schematic, cross-sectional view of the pressing machine of
FIG. 5A as viewed from a front side thereof;
FIG. 6 is a schematic, cross-sectional view of a further embodiment of a
mechanical pressing machine of the invention as viewed from a front side
thereof;
FIG. 7 is a schematic, cross-sectional view of the pressing machine of FIG.
6 as viewed from a side thereof;
FIGS. 8 and 9 are views similar to FIG. 6, explanatory of the operation of
the pressing machine of FIG. 6; and
FIG. 10 is a schematic, cross-sectional view of a still further embodiment
of a mechanical pressing machine of the invention as viewed from a front
side thereof.
DESCRIPTION OF THE PREFERRED EMBODIMENTS
FIG. 1 is a schematic, cross-sectional view of a preferred embodiment of a
mechanical pressing machine of the present invention as viewed from a
front side thereof, and FIG. 2 is a schematic, cross-sectional view of the
mechanical pressing machine as viewed from a side thereof. In FIG. 1, an
upright-type frame 1 includes a lower support portion 2, an intermediate
support portion 3, and an upper support portion 4. A bed 5 is mounted on
the lower support portion 2 of the frame 1, and a slider. 7 is mounted on
the intermediate support portion 3 through a slide guide 6 so as to slide
in a vertical direction. A die of the press comprises a lower die mounted
on an upper surface of the bed 5, and an upper die mounted on a lower
surface of the slider 7. A dynamic balancer 9 equal in weight to the
slider 7 is mounted on the upper support portion 4 through a slide guide 8
so as to slide in the vertical direction.
In FIG. 2, a cam shaft 10 extends horizontally through a space between the
intermediate support portion 3 and the upper support portion 4 of the
frame 1, and is rotatably supported by bearings 11 and 12. A flywheel 14
is fixedly secured to one end of the cam shaft 10 through a clutch/brake
13, and this flywheel 14 is driven by a motor (not shown) through a belt
15. A press cam 16 is fixedly mounted on a central portion of the cam
shaft 10, and has at its periphery a cam surface which is in contact with
cam followers 19 and 20 rotatably mounted through respective studs 17 and
18 on a central portion of the upper surface of the slider 7 and a central
portion of the lower surface of the dynamic balancer 9, respectively.
In FIGS. 1 and 2, two pairs of right and left link mechanisms are provided
between the upper surface of the slider 7 and the lower surface of the
dynamic balancer 9, and are disposed generally around the press cam 16,
the two pairs being disposed at the front side portion and the rear side
portion of the frame 1, respectively. Each of the link mechanisms
comprises a first link 21 pivotally connected at its one end to the upper
surface of the slider 7, and a second link 22 pivotally connected at its
one end to the lower surface of the dynamic balancer 9. A cam follower 24
is rotatably mounted on the other ends (each having a fork-like shape) of
the first and second links 21 and 22 through a stud 23. A pair of dynamic
balancer cams 25 and 26 are fixedly mounted on the cam shaft 10, and each
of the dynamic balancer cams 25 and 26 has at its periphery a cam surface
which is in contact with the cam followers 24 of the corresponding pair of
right and left link mechanisms. The press cam 16, as well as the dynamic
balancer cams 25 and 26, has an elliptical shape which is 180.degree.
symmetrical. The elliptical shape of the dynamic balancer cams 25 and 26
is longer than that of the press cam 16. These cams 16, 25 and 26 may have
any other suitable shape than such an elliptical shape.
The operation of the above mechanical pressing machine will now be
described. The motor (not shown) is rotated, and its rotational force is
transmitted to the flywheel 14 through the belt 15, so that the press cam
16 and the dynamic balancer cams 25 and 26 are rotated through the cam
shaft 10. The slider 7 and the dynamic balancer 9 are connected together
by the two pairs of link mechanisms each comprising the first and second
links 21 and 22, and are held or constrained in contact with the
peripheral surface of the press cam 16 through the respective cam
followers 19 and 20. Therefore, when the dynamic balancer cams 25 and 26
rotate from the respective positions shown in FIG. 3, each pair of right
and left link mechanisms are expanded or urged away from each other
through the cam followers 24 to move the slider 7 and the dynamic balancer
9 toward each other. This movement of the slider 7 and the dynamic
balancer 9 is restrained by contact of the peripheral surface of the press
cam 16 with the cam followers 19 and 20, so that a motion, controlled by
the cam surface of the press cam 16, is imparted to the slider 7 and the
dynamic balancer 9. As a result, the inertia force, produced in the
ascending slider 7, is canceled by the oppositely-directed inertia force
produced in the descending dynamic balancer 9 (which is equal in weight to
the slider 7), and therefore the dynamic precision can be maintained
regardless of a change in speed. When the cam shaft 10 rotates 90.degree.
from the position of FIG. 3 where the slider 7 is in its lower dead
center, the slider 7 is brought into its upper dead center as shown in
FIG. 4. When the cam shaft 10 further rotates 90.degree. (that is,
180.degree. from the initial position), the slider 7 is again brought into
its lower dead center as shown in FIG. 3, thus completing one stroke.
Therefore, the slider 7 effects two strokes per revolution of the cam
shaft 10.
Although this embodiment is directed to the single-point press comprising
the single press cam 16 and the two dynamic balancer cams 25 and 26, it
may be modified into a two-point press as shown in FIGS. 5A and 5B, in
which two press cams 16A and 16B and one dynamic balancer cam 25A are
fixedly mounted on the cam shaft 10. In this case, four cam followers 19A,
19B, 20A and 20B are needed for the two press cams 16A and 16B, and only
one pair of right and left link mechanisms are required for the dynamic
balancer cam 25A.
As described above, in the above embodiment, thanks to the provision of the
press cam 16 and the dynamic balancer cams 25 and 26 which are different
in shape from the press cam 16, the upward and downward movement of the
slider 7 can be perfectly controlled, and besides the vertically-opposite
motion can be imparted to the dynamic balancer 9 having the same load as
that of the slider 7. Therefore, with respect to an unbalanced inertia
force produced in the slider 7, a similar inertia force, produced by
movement of the dynamic balancer 9 in the opposite direction, is imparted
to the slider 7 through the link mechanisms, thereby canceling this
unbalanced inertia force. As a result, deflection of the whole of the
press is reduced, so that the dynamic precision can be enhanced. Each of
the cam followers 24, interconnecting the first and second links 21 and 22
of a respective one of the link mechanisms interconnecting the slider 7
and the dynamic balancer 9, is not supported by the frame 1 and other
members, and is controlled in movement only by the dynamic balancer cam
25, 26 in a free condition. Therefore, the transmission efficiency is
high, and the high-speed operation can be suitably carried out. And
besides, since the slider 7 is driven by the cam, the timings of the
ascending stroke and descending stroke of the slider, as well as the
motion curve thereof, can be freely designed, and for example, the timing
of the upper dead center or the timing of the lower dead center can be
determined to be earlier.
FIGS. 6 to 9 show another embodiment of a mechanical pressing machine of
the invention, and correspond to FIGS. 1 to 4, respectively. This
embodiment of FIGS. 6 to 9 differs from the embodiment of FIGS. 1 to 4
(described above in detail) in that that portion where one end of each of
first and second links 21 and 22 is pivotally connected is different.
Those different portions will now be described in detail.
In the embodiment of FIGS. 1 to 4, the one end of each first link 21 is
pivotally connected to the upper surface of the slider 7, and the one end
of each second link 22 is pivotally connected to the lower surface of the
dynamic balancer 9. In the embodiment of FIGS. 6 to 9, the one end of each
first link 21 is mounted on a stud 17 (on which cam followers 19, mounted
on an upper surface of a slider 7, is mounted) in coaxial relation
thereto, and the one end of each second link 22 is mounted on a stud 18
(on which cam followers 20, mounted on a lower surface of a dynamic
balancer cam 9, is mounted) in coaxial relation thereto.
With this construction, this embodiment has the following advantages:
The number of the component parts is smaller, and the overall construction
of the press is simple.
The slider and the dynamic balancer have such shapes that they can be
easily worked or machined, and the required strength of each link support
portion can be easily secured.
The link support positions in this embodiment of FIGS. 6 to 9 are thus
different from those in the embodiment of FIGS. 1 to 4, and more
specifically the first links are connected to the common shaft on the
slider whereas the second links are connected to the common shaft on the
dynamic balancer (The two common shafts are disposed in a centered
manner), and therefore each link can be made the longest, so that the
longest stroke can be obtained among those mechanisms employing such
linkage arrangement.
FIG. 10 shows a further embodiment of a mechanical pressing machine of the
invention, and is a view explanatory of suitable conditions with respect
to the connection of first links 21 to an upper surface of a slider 7 as
well as the connection of second links 22 to a lower surface of a dynamic
balancer 9.
In the mechanical pressing machine of this embodiment, preferably, the pair
of right and left link mechanisms each comprising the first link 21 and
the second link are mounted in the following manner:
(1) The distance A between the axis of pivotal movement of one end of the
first link 21 (connected to the upper surface of the slider 7) and the
center (axis) of the cam shaft 10 is equal to the distance A between the
axis of pivotal movement of one end of the second link 22 (connected to
the lower surface of the dynamic balancer 9) and the center (axis) of the
cam shaft 10.
(2) The distance B between the center (axis) of the cam shaft 10 and the
axis of pivotal movement of the one end of the right second link 22
(connected to the dynamic balancer 9) is equal to the distance B between
the center (axis) of the cam shaft 10 and the axis of pivotal movement of
the one end of the left second link 22 (connected to the dynamic balancer
9).
(3) As the distance between the upper and lower cam followers 20 and 19
increases, the distance between right and left cam followers 24 decreases,
and in contrast, as the distance between the upper and lower cam followers
20 and 19 decreases, the distance between the right and left cam followers
24 increases. More specifically, if the distance between the center (axis)
of the cam shaft 10 and the center (axis) of each of the right and left
cam followers 24 is represented by C, the distance C is always larger than
the distance B.
In the embodiment of FIGS. 6 to 9, if the distance between the center of
the cam shaft 10 and the center of the stud 23 is represented by D, the
distance A is equal to the distance D, and the distance B is zero (0).
As described in the above embodiment, there is provided the dynamic
balancer which moves in a direction opposite to the direction of movement
of the slider when the slider moves, and therefore an unbalanced inertia
force, produced during the reciprocal movement of the slider, is canceled,
and deflection of the whole of the pressing machine is reduced, thereby
enhancing the dynamic precision, and vibrations and noises are reduced.
And besides, the pressing machines of the invention are simpler in
construction, and achieve higher precision as compared with the above
earlier-proposed pressing machines, and the slider and the dynamic
balancer are moved simultaneously not by sliding contact but by rolling
contact between the cams and the cam followers, and therefore the
transmission efficiency is enhanced, and the high-speed operation can be
suitably carried out.
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